Boston’s public radio station, WBUR, released a new poll on Thursday that shows Massachusetts Republican Senator Scott Brown leads Democratic challenger Sen. Elizabeth Warren (D-MA) by 4 points, 47 to 43. The poll represents a 6 point drop for Warren, who was up 2 points in a WBUR poll conducted last month.

Brown’s new lead suggests concerns over Warren’s character have cut into her support among Massachusetts voters. The poll was conducted October 5 to 7, and has a 4.4 percent point margin of error:

The latest WBUR poll finds that 60 percent of Brown’s supporters thinks it’s “very important” that the candidate they support “will compromise with the other party more often when in the Senate.” Only 41 percent of Warren supporters think that’s an important consideration. . .

Throughout the year, Brown has tried to portray Warren as someone voters can’t trust. It began with questioning her motives for listing herself as Native American in a law school registry. And the WBUR poll finds that this is working to Brown’s advantage with a sizable minority of voters. Thirty-one percent of Brown’s supporters see the issue as “very important.”

In recent weeks, Brown has broadened his attack on Warren’s credibility. He has questioned her role in advising an insurance company defending claims of victims of asbestos contamination. That’s an issue that resonates with Jason Cherson, of West Roxbury.

Warren’s biggest advantage remains among people who consider which party “will control the U.S. Senate after this election,” Seventy-one percent of Warren supporters say that’s “very important.” But for now, that’s not important enough in most voters’ minds to offset their preference for Scott Brown.